London, Mar 15 : The cast and crew of hit sitcom 'How I Met Your Mother' have been forced to wear wristbands on the set while Britney Spears is filming her cameo role - in order to prevent onlookers from clicking the troubled pop star at the studio.
Because of the security measure, show's star Neil Patrick Harris, who plays womaniser Barney, was denied entry to the studio as he was not wearing a wrist band.
"They wouldn't let me on the stage because I didn't have the proper wristband. I said to the security people: 'Lady, I am actually on the show.' We had words and I eventually made it on set," The Sun quoted Harris, as saying.
Though annoyed, Harris, best known as Doogie from the eighties show Doogie Howser MD, said that Britney has been "very professional" in her cameo role as dermatologist's secretary Abby. "She's good. We did the run through on Tuesday, she seemed a little nervous, she wore the big sunglasses the whole time. I think that's a bit of a security blanket. But she seems very professional," he said.
The show featuring the 'Toxic' singer is set to be aired on March 24 on US cable channel CBS.